Plate heat exchanger and refrigeration air conditioner

ABSTRACT

It is aimed to enhance the strength of a plate heat exchanger while maintaining the heat exchange capability of the plate heat exchanger. A plate heat exchanger  20  is configured with a plurality of stacked plates  2  and  3 . Each of the plates  2  and  3  includes at four corners thereof a first inlet hole  5  which acts as an inlet for a first fluid, a first outlet hole  6  which acts as an outlet for the first fluid, a second inlet hole  7  which acts as an inlet for a second fluid, and a second outlet hole  8  which acts as an outlet for the second fluid. Each of the plates  2  and  3  and an adjacent plate define therebetween a first flow path for passing the first fluid and a second flow path for passing the second fluid, so as to exchange heat between the first fluid and the second fluid. In each of the plates  2  and  3 , a longitudinal length L 1  is 4 or more times a lateral length L 2.

TECHNICAL FIELD

This invention relates to a plate heat exchanger configured with aplurality of stacked plates and a refrigeration air conditionerincluding the plate heat exchanger, for example.

BACKGROUND ART

Patent Document 1 discusses a plate heat exchanger in which a fluidinlet hole and a fluid outlet hole are elliptically shaped. PatentDocument 1 also discusses a plate heat exchanger in which the diameterof a fluid inlet hole and the diameter of a fluid outlet hole areidentical in size.

Patent Document 2 discusses a plate heat exchanger in which the diameterof a fluid inlet hole and the diameter of a fluid outlet hole aredifferent in size. Patent Document 2 also discusses a plate heatexchanger which includes reinforcement members for a fluid inlet holeand a fluid outlet hole, thereby providing enhanced strength.

CITATION LIST Patent Documents

-   Patent Document 1: JP 9-72685 A-   Patent Document 2: JP 7-508581 W

DISCLOSURE OF INVENTION Technical Problem

Conventional plate heat exchangers have the following problems (1) to(3):

(1) Plate heat exchangers in general have thin plates, so that thestrength is low.

(2) In a plate exchanger which includes reinforcement members for aninlet hole and an outlet hole, dirt tends to accumulate in the inlethole and the outlet hole.

(3) When large volumes of fluid flow through a plate heat exchanger,there will be a point where the flow rate reaches a limit at a fluidinlet hole and a fluid outlet hole. Accordingly, to process largevolumes of fluid, the inlet hole and the outlet hole need to have largeropening areas. However, to enlarge the opening areas of the inlet holeand the outlet hole, the widths of the inlet hole and the outlet holemust be increased. Increasing the widths of the inlet hole and theoutlet hole reduces strength, as well as reduces a heat transfer area.That is, the plate heat exchanger in which the inlet hole and the outlethole have large opening areas has drawbacks in terms of strength andheat exchange capability.

This invention aims to enhance the strength of a plate heat exchangerwhile maintaining the heat exchange capability of the plate heatexchanger, for example.

Solution to Problem

A plate heat exchanger according to this invention is, for example,

a plate heat exchanger configured with a plurality of stacked plates,

wherein each plate of the plurality of stacked plates includes:

a first inlet hole which acts as an inlet for a first fluid, the firstinlet hole being located near one edge in a longitudinal direction;

a first outlet hole which acts as an outlet for the first fluid, thefirst outlet hole being located near another edge opposite from thefirst inlet hole in the longitudinal direction;

a second inlet hole which acts as an inlet for a second fluid, thesecond inlet hole being located near one edge in the longitudinaldirection; and

a second outlet hole which acts as an outlet for the second fluid, thesecond outlet hole being located near another edge opposite from thesecond inlet hole in the longitudinal direction,

wherein the each plate and an adjacent plate define therebetween eitherone of a first flow path and a second flow path, the first flow pathpassing the first fluid entered from the first inlet hole to the firstoutlet hole such that the first fluid spreads in a lateral direction,and the second flow path passing the second fluid entered from thesecond inlet hole to the second outlet hole such that the second fluidspreads in the lateral direction, and the each plate exchanges heatbetween the first fluid flowing through the first flow path and thesecond fluid flowing through the second flow path, and

wherein the each plate is configured such that a length in thelongitudinal direction is 4 or more times a length in the lateraldirection.

Advantageous Effects of Invention

A plate heat exchanger according to this invention is configured suchthat a length in a longitudinal direction is 4 or more times a length ina lateral direction. Accordingly, stress applied to edges of each platecan be reduced. Thus, the plate heat exchanger according to thisinvention provides enhanced strength.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a plate heat exchanger 20;

FIG. 2 is a front view of a reinforcement side plate 1;

FIG. 3 is a front view of a second plate 2;

FIG. 4 is a front view of a first plate 3;

FIG. 5 is a front view of a reinforcement side plate 4;

FIG. 6 is an exploded perspective view of the plate heat exchanger 20;

FIG. 7 is a diagram showing dimensions of the plates 2 and 3 of theplate heat exchanger 20;

FIG. 8 is a diagram depicting the relationship between stress and theratio of a longitudinal length and a lateral length of the plates 2 and3.

FIG. 9 is a diagram depicting the relationship between the weight of theplate heat exchanger 20 and the ratio of the longitudinal length and thelateral length of the plates 2 and 3.

FIG. 10 is a diagram showing the plates 2 and 3 in which the diametersof first inlet and outlet holes are smaller than the diameters of secondinlet and outlet holes.

FIG. 11 is a diagram showing the plate heat exchanger 20 in which thenearer each of the plates 2 and 3 is to the reinforcement side plate 1,the smaller the diameter of a first inlet hole 5.

FIG. 12 is a diagram showing dimensions of the plates 2 and 3 in whichthe inlet and outlet holes are positioned nearer to four corners of eachplate.

FIG. 13 is a diagram describing a flow of a first fluid on the firstplate 3 in which the inlet and outlet holes are positioned nearer to thefour corners of the plate.

FIG. 14 is a diagram describing corrugations 9 of the first plate 3 inwhich the inlet and outlet holes are positioned nearer to the fourcorners of the plate.

FIG. 15 is a diagram showing the corrugations 9 of the second plate 2 inwhich the inlet and outlet holes are positioned nearer to the fourcorners of the plate.

FIG. 16 is a diagram showing the corrugations 9 of the first plate 3 inwhich the inlet and outlet holes are positioned nearer to the fourcorners of the plate.

FIG. 17 is a diagram showing the plates 2 and 3 in which the first inletand outlet holes are differently shaped from the second inlet and outletholes.

FIG. 18 is a diagram showing the plates 2 and 3 in which the first inletand outlet holes are differently shaped from the second inlet and outletholes.

FIG. 19 is a diagram showing the plates 2 and 3 in which the first inletand outlet holes are differently shaped from the second inlet and outletholes.

FIG. 20 is a diagram comparing a case in which the first inlet andoutlet holes and the second inlet and outlet holes are identical inshape, and a case in which the first inlet and outlet holes and thesecond inlet and outlet holes are different in shape.

FIG. 21 is a diagram showing the plates 2 and 3 in which the first inletand outlet holes and the second inlet and outlet holes are formed in anidentical non-circular shape.

FIG. 22 is a diagram showing the plates 2 and 3 in which the first inletand outlet holes and the second inlet and outlet holes are formed in anidentical non-circular shape.

FIG. 23 is a diagram showing the plates 2 and 3 in which the first inletand outlet holes and the second inlet and outlet holes are formed in anidentical non-circular shape.

FIG. 24 is a diagram showing the plates 2 and 3 in which the first inletand outlet holes and the second inlet and outlet holes are formed in anidentical non-circular shape; and

FIG. 25 is a diagram showing a heating and hot water system 29,

DESCRIPTION OF EMBODIMENTS First Embodiment

FIGS. 1 to 6 are diagrams describing a plate heat exchanger 20 accordingto a first embodiment. FIG. 1 is a side view of the plate heat exchanger20. FIG. 2 is a front view of a reinforcement side plate 1. FIG. 3 is afront view of a second plate 2. FIG. 4 is a front view of a first plate3. FIG. 5 is a front view of a reinforcement side plate 4. FIG. 6 is anexploded perspective view of the plate heat exchanger 20.

As shown in FIG. 1, the plate heat exchanger 20 includes a plurality ofstacked plates 2 and 3. The plate heat exchanger 20 also includes thereinforcement side plates 1 and 4 stacked at the forefront (an A side inFIG. 1) and the rear end (a B side in FIG. 1), respectively.

As shown in FIGS. 3 and 4, each of the plates 2 and 3 is formed as aplate of an approximately rectangular shape. Each of the plates 2 and 3includes a first inlet hole 5 near one edge (an upper side) in along-side (longitudinal) direction of the approximately rectangularshape. Each of the plates 2 and 3 includes a first outlet hole 6 nearanother edge (a lower side) in the longitudinal direction opposite fromthe first inlet hole 5. Each of the plates 2 and 3 includes a secondinlet hole 7 near the same edge (the lower side) in the longitudinaldirection as the first outlet hole 6. Each of the plates 2 and 3includes a second outlet hole 8 near the same edge (the upper side) inthe longitudinal direction as the first inlet hole 5. Each of the plates2 and 3 includes the first inlet hole 5 and the first outlet hole 6 nearthe same edge (a left side) in a short-side (lateral) direction of theapproximately rectangular shape. Each of the plates 2 and 3 includes thesecond inlet hole 7 and the second outlet hole 8 near another edge (aright side) in the lateral direction opposite from the first inlet hole5 and the first outlet hole 6.

That is, the first inlet hole 5, the first outlet hole 6, the secondinlet hole 7, and the second outlet hole 8 are provided at four cornersof each of the plates 2 and 3. The first inlet hole 5 and the firstoutlet hole 6 will be referred to as first inlet and outlet holes.Likewise, the second inlet hole 7 and the second outlet hole 8 will bereferred to as second inlet and outlet holes.

Like the plates 2 and 3, the reinforcement side plates 1 and 4 are alsoformed as plates in an approximately rectangular shape, as shown inFIGS. 2 and 5. As shown in FIG. 2, the reinforcement side plate 1stacked at the forefront includes the first inlet hole 5 (a first inletduct), the first outlet hole 6 (a first outlet duct), the second inlethole 7 (a second inlet duct), and the second outlet hole 8 (a secondoutlet duct) at the same positions as in the plates 2 and 3.

On the other hand, as shown in FIG. 5, the reinforcement side plate 4stacked at the rear end does not include the first inlet hole 5, thefirst outlet hole 6, the second inlet hole 7, and the second outlet hole8. In FIG. 5, the positions of the first inlet hole 5, the first outlethole 6, the second inlet hole 7, and the second outlet hole 8 areindicated by dashed lines, but these holes are not actually present inthe reinforcement side plate 4.

Each of the plates 2 and 3 and the reinforcement side plate 1 arestacked such that the respective first inlet holes 5, first outlet holes6, second inlet holes 7, and second outlet holes 8 are aligned with oneanother. The second plate 2 and the first plate 3 are stackedalternately.

The plates 2 and 3 and the reinforcement side plates 1 and 4 are formedapproximately identically in an approximately rectangular shape.

As shown in FIGS. 3 and 4, each of the plates 2 and 3 has a plurality ofV-shaped concave portions and convex portions (corrugations 9) arrangedin longitudinal arrays. The corrugations 9 have ends 13 at both sides inthe lateral direction. The corrugations 9 are formed in the shape of a Vhaving turning points 12, each turning point 12 being longitudinallymisaligned with respect to the corresponding ends 13 at both sides. Thepitch (width) of the corrugations 9 is indicated as W in FIG. 4. Thecorrugations 9 are provided such that the direction thereof is reversedbetween the second plate 2 and the first plate 3. That is, in the secondplate 2, the corrugations 9 are formed in the shape of a V with eachturning point 12 positioned lower than the corresponding ends 13 at bothsides. On the other hand, in the first plate 3, the corrugations 9 areformed in the shape of a V (a reversed V) with each turning point 12positioned higher than the corresponding ends 13 at both sides.

In this way, the V-shaped corrugations 9 are formed in the plates 2 and3 by reversing the direction of the V shape between the plates 2 and 3.By stacking the plates 2 and 3 alternately, flow paths with high heattransfer efficiency are defined between the plates 2 and 3. That is, asshown in FIG. 6, a first flow path is defined between the back surfaceof the second plate 2 and the front surface of the first plate 3 suchthat a first fluid entered from the first inlet hole 5 flows to thefirst outlet hole 6. Likewise, a second flow path is defined between theback surface of the first plate 3 and the front surface of the secondplate 2 such that a second fluid entered from the second inlet hole 7flows to the second outlet hole 8.

The first fluid flowing through the first flow path is heat-exchangedwith the second fluid flowing through the second flow path via theplates 2 and 3.

FIG. 7 is a diagram showing dimensions of the plates 2 and 3 of theplate heat exchanger 20. In FIG. 7, a length L1 indicates a length ofthe plates 2 and 3 in the longitudinal direction. A length L2 indicatesa length of the plates 2 and 3 in the lateral direction. A length L3indicates a length from the first inlet hole 5 to a plate edge proximateto the first inlet hole 5 in the lateral direction. A length 4 indicatesa length from the first outlet hole 6 to a plate edge proximate to thefirst outlet hole 6 in the lateral direction. A length L5 indicates alength from the second inlet hole 7 to a plate edge proximate to thesecond inlet hole 7 in the lateral direction. A length L6 indicates alength from the second outlet hole 8 to a plate edge proximate to thesecond outlet hole 8 in the lateral direction.

FIG. 8 is a diagram depicting the relationship between stress and theratio (length ratio) of the longitudinal length and the lateral lengthof the plates 2 and 3. The horizontal axis in FIG. 8 depicts the ratio(length ratio) between the longitudinal length and the lateral length ofthe plates 2 and 3. That is, the horizontal axis in FIG. 8 depicts theratio of the longitudinal length L1 of the plates 2 and 3 to the laterallength L2 of the plates 2 and 3. The vertical axis in FIG. 8 depicts thestress applied to the edges (periphery) of the plates 2 and 3. In FIG.8, stress is expressed as a stress ratio. The reference value of thestress ratio is a value indicated by the second point from the right,namely, a point P, in FIG. 8. Each point in FIG. 8 represents acalculated value of a stress ratio relative to a length ratio. The linein FIG. 8 represents values calculated from each point by using aleast-square method.

As shown in FIG. 8. the shorter the lateral length L2 of the plates 2and 3 is relative to the longitudinal length L1 of the plates 2 and 3,the smaller the stress applied to the periphery of the plates 2 and 3.Thus, the length L2 should preferably be as short as possible relativeto the length L1. Specifically, the length L2 should preferably beshortened such that the length L1 is 4 or more times the length L2.However, due to limitations on the manufacture of the plate heatexchanger 20, the length L2 cannot be shortened significantly.Accordingly, the length L2 should preferably be shortened such that thelength L1 is approximately from 4 to 6.5 times the length L2.

By making the lengths L3, L4, L5, and L6 shorter, the stress applied tothe edges of the plates 2 and 3 is reduced. Specifically, the lengthsL3, L4, L5, and L6 should preferably be set to not more than 6 percentof the lateral length L2 of the plates 2 and 3. The lengths L3, L4, L5,and L6 may be set to not more than 5.6 mm, irrespective of the laterallength L2 of the plates 2 and 3. However, due to limitations on themanufacture of the plate heat exchanger 20, the lengths L3, L4, L5, andL6 cannot be shortened significantly. Accordingly, the lengths L3, L4,L5, and L6 should preferably be set to between not less than 3 percentand not more than 6 percent of the lateral length L2 of the plates 2 and3. Likewise, the lengths L3, L4, L5, and L6 should preferably be set tonot less than 3 mm and not more than 5.6 mm.

FIG. 9 is a diagram depicting the relationship between the ratio of thelongitudinal length and the lateral length of the plates 2 and 3 and theweight of the plate heat exchanger 20. Specifically, FIG. 9 depicts theextent to which the weight of the plate heat exchanger 20 can be reducedby shortening the lateral length of the plates 2 and 3 without changingthe longitudinal length of the plates 2 and 3.

As in FIG. 8, the horizontal axis in FIG. 9 depicts the ratio (lengthratio) of the longitudinal length and the lateral length of the plates 2and 3. The vertical axis in FIG. 9 depicts the reduction ratio of theweight of the plate heat exchanger 20. The reduction ratio of the weightof the plate heat exchanger 20 is a value calculated based on the weightof the plate heat exchanger 20 manufactured with the length ratioselected as the reference value of the stress ratio in FIG. 8 (the valueindicated by the second point from the right, namely, the point P).

By making the length L2 shorter, the size of the plate heat exchanger 20is reduced, so that the weight of the plate heat exchanger 20 can bereduced. However, by making the length L2 shorter, not only the weightcan be reduced due to the reduced overall size, but also the thicknessof the plates 2 and 3 and the thickness of the reinforcement side plates1 and 4 can be reduced, so that the weight can be reduced further. Thatis, by making the length L2 shorter, the strength of the plate heatexchanger 20 is enhanced. Accordingly, the thickness of the plates 2 and3 and the thickness of the reinforcement side plates 1 and 4 can bereduced, so that the weight of the plate heat exchanger 20 can bereduced.

As a result, by shortening the length L2 relative to the length L1, theweight of the plate heat exchanger 20 can be reduced more than by theweight reduction due to reduction in overall size.

As described above, in the plate heat exchanger 20 according to thefirst embodiment, the lateral length L2 of the plates 2 and 3 isshortened relative to the longitudinal length L1 of the plates 2 and 3,so that the strength of the plate heat exchanger 20 is enhanced.

In the plate heat exchanger 20 according to the first embodiment, thelengths between the inlet or outlet holes 5, 6, 7, and 8 and the plateedge (the lengths L3, L4, L5, and L6) are also shortened, so that thestrength of the plate heat exchanger 20 is enhanced.

Furthermore, due to the enhanced strength of the plate heat exchanger20, the weight of the plate heat exchanger 20 can be reduced.

By making the lateral length L2 shorter, a fluid entered from the firstinlet hole 5 or the second inlet hole 7 is also facilitated to spread inthe lateral direction. This eliminates the need to provide distributionfacilitating members around the first inlet hole 5 and the second inlethole 7 so as to facilitate spreading of the fluid. The enhanced strengthof the plate heat exchanger 20 also eliminates the need to providereinforcement members around the inlet holes (the first inlet hole 5,the second inlet hole 7). Thus, because there is no need to providedistribution facilitating members or reinforcement members, pressworking of the plates 2 and 3 is simplified. Accordingly, the cost ofmanufacturing the plate heat exchanger 20 can be reduced. Variation inheight of the corrugations 9 can also be reduced. That is, the plateheat exchanger 20 of stable quality can be manufactured.

When stagnation occurs in a fluid in a plate heat exchanger, dirt andscales tend to accumulate in a location where the stagnation occurred.The plates 2 and 3 are prone to corrosion in the location where dirt andscales are accumulated. If a heat exchanger in which stagnation mayoccur in a fluid is used in an evaporator, a drift may occur causing anuneven distribution of temperature. This may cause the fluid to freezein some locations. When the fluid freezes, the strength of the heatexchanger is reduced. However, in the plate heat exchanger 20 accordingto the first embodiment, the lateral length of the plates 2 and 3 isshort, so that the possibility of stagnation in a fluid is lessened.Thus, the possibility of accumulation of dirt and scales is lessened,and the strength is not reduced. The plate heat exchanger 20 accordingto the first embodiment is effective not only when the fluid is waterbut also for other types of fluid which have a tendency to drift due toa small density and a high pressure loss (e.g., a hydrocarbonrefrigerant or a low-GWP refrigerant). With a chlorofluorocarbonrefrigerant, effectiveness is also provided for preventing accumulationof refrigerant oil in the heat exchanger. This permits power consumptionto be reduced in an apparatus using the plate heat exchanger 20according to the first embodiment.

Second Embodiment

In a second embodiment, there will be described the plate heat exchanger20 in which the diameters of the first inlet and outlet holes aresmaller than the diameters of the second inlet and outlet holes. Thatis, in the second embodiment, there will be described the plate heatexchanger 20 in which the opening areas of the first inlet and outletholes are smaller than the opening areas of the second inlet and outletholes.

FIG. 10 is a diagram showing the plates 2 and 3 in which the diametersof the first inlet and outlet holes are smaller than the diameters ofthe second inlet and outlet holes.

For example, when the plate heat exchanger 20 is used to exchange heatbetween a liquid such as water and a refrigerant such aschlorofluorocarbon, there is a risk that the plates may wear out (becomethinner) due to erosion at an inlet hole for the liquid (the secondinlet hole 7 here). For this reason, the diameters of the inlet andoutlet holes for the liquid (the second inlet hole 7, the second outlethole 8) need to be sufficiently large. However, there is no need to makethe diameters of the inlet and outlet holes for the refrigerant (thefirst inlet hole 5, the first outlet hole 6) as large as the diametersof the inlet and outlet holes for the liquid (the second inlet hole 7,the second outlet hole 8). That is, the diameters of the first inlethole 5 and the first outlet hole 6 may be smaller than the diameters ofthe second inlet hole 7 and the second outlet hole 8. When the diametersof the first inlet hole 5 and the first outlet hole 6 are reduced asdescribed above, the lateral length of the plates 2 and 3 can becorrespondingly shortened. Thus, the strength of the plate heatexchanger 20 is enhanced, and the weight of the plate heat exchanger 20can be reduced, as described in the first embodiment.

The refrigerant is not limited to chlorofluorocarbon, and may also be ahydrocarbon refrigerant or a low-GWP refrigerant. A CO2 refrigerantrequires the plate heat exchanger 20 to be strong due to a high workingpressure. When the CO2 refrigerant is used, it is especially effectiveto configure the inlet and outlet holes for the refrigerant to besmaller than the inlet and outlet holes for the liquid. Since the CO2refrigerant has a higher density and a smaller pressure loss compared tothe chlorofluorocarbon refrigerant, the diameters of the first inlethole 5 and the first outlet hole 6 can be further reduced.

FIG. 11 is a diagram showing the plate heat exchanger 20 configured suchthat the nearer each of the plates 2 and 3 is to the reinforcement sideplate 1, the smaller the diameter of the first inlet hole 5.

The plate heat exchanger 20 shown in FIG. 11 is configured such that notonly the diameters of the first inlet and outlet holes are smaller thanthe diameters of the second inlet and outlet holes, but also the nearereach of the stacked plates 2 and 3 is to the reinforcement side plate 1,the smaller the diameter of the first inlet hole 5. That is, the nearereach of the stacked plates 2 and 3 is to the reinforcement side plate 1than to the reinforcement side plate 4, the smaller the diameter of thefirst inlet hole 5. In other words, the nearer each of the stackedplates 2 and 3 is to the entrance side of the first fluid, the smallerthe diameter of the first inlet hole 5. Specifically, the first inlethole 5 is extremely small like a fine nozzle in the plates 2 and 3stacked near the reinforcement side plate 1.

Because the first inlet hole 5 is extremely small in the plates 2 and 3stacked near the reinforcement side plate 1, the first fluid can flow athigh speed even when a large number of the plates 2 and 3 are stacked.This also facilitates distribution of the first fluid toward the plates2 and 3 stacked near the reinforcement side plate 4.

Furthermore, the nearer each of the stacked plates 2 and 3 is to thereinforcement side plate 4, the larger the diameter of the first inlethole 5 is. This facilitates an even distribution of the first fluidthrough the first flow path defined by each pair of the plates 2 and 3.

Third Embodiment

In a third embodiment, there will be described the plate heat exchanger20 in which the inlet and outlet holes are positioned not only nearer tothe edges of each plate in the lateral direction, but also nearer to theedges of each plate in the longitudinal direction. That is, in the thirdembodiment, there will be described the plate heat exchanger 20 in whichthe inlet and outlet holes are positioned nearer to the four corners ofthe plates 2 and 3.

FIG. 12 is a diagram showing dimensions of the plates 2 and 3 in whichthe inlet and outlet holes are positioned nearer to the four corners ofeach plate. In FIG. 12, a length L7 indicates a length from the firstinlet hole 5 to a plate edge proximate to the first inlet hole 5 in thelongitudinal direction. A length L8 indicates a length from the firstoutlet hole 6 to a plate edge proximate to the first outlet hole 6 inthe longitudinal direction. A length L9 indicates a length from thesecond inlet hole 7 to a plate edge proximate to the second inlet hole 7in the longitudinal direction. A length L10 indicates a length from thesecond outlet hole 8 to a plate edge proximate to the second outlet hole8 in the longitudinal direction.

The lengths L7, L8, L9, and L10 are approximately equivalent to thelengths L3, L4, L5, and L6 shown in FIG. 7, respectively. In this way,by making the lengths L7, L8, L9, and L10 shorter, the stress applied tothe periphery of each plate can be further reduced.

Specifically, in the plates 2 and 3 shown in FIG. 12, the diameters ofthe first inlet and outlet holes are smaller than the diameters of thesecond inlet and outlet holes. Accordingly, the centers of the firstinlet and outlet holes are positioned nearer to the corners of theplates 2 and 3 relative to the centers of the second inlet and outletholes.

In this way, by positioning the first inlet and outlet holes havingsmaller diameters (the first inlet hole 5, the first outlet hole 6)nearer to the four corners of the plates 2 and 3, the distance from thefirst inlet hole 5 to the first outlet hole 6 is increased. That is, thelength of the first flow path is increased. Accordingly, the heattransfer area is increased, and the heat exchange capability of theplate heat exchanger 20 is enhanced.

FIG. 13 is a diagram describing a flow of the first fluid on the firstplate 3 in which the inlet and outlet holes are positioned nearer to thefour corners of the plate. FIG. 13 only applies to the first plate 3instead of the plates 2 and 3. This is because a sealing portion 11 isshown in FIG. 13. That is, the sealing portion 11 is provided atdifferent locations between the second plate 2 and the first plate 3.

By positioning the first inlet hole 5 having a smaller diameter nearerto the corner of the plates 2 and 3, an entrance region 10 for the firstflow path can be provided near the first inlet hole 5. The entranceregion 10 is a narrow region between the plate edge and the sealingportion 11. This means that the width of the entrance region 10 (alength L11 from the plate edge to the sealing portion 11) is narrowerthan the lateral width (the length L2) of the first plate 3. The firstfluid entered from the first inlet hole 5 passes through the narrowentrance region 10, then spreads in the lateral direction of the plateheat exchanger 20, and flows to the first outlet hole 6.

The sealing portion 11 is a wall which prevents the first fluid enteredfrom the first inlet hole 5 from flowing to the second outlet hole 8.The sealing portion 11 is formed as a protrusion raised in the stackingdirection of the plates 2 and 3. The sealing portion 11 is normallyprovided around the second outlet hole 8 in a circular shape. However,the sealing portion 11 is provided here, starting from near the edge(the upper side) in the longitudinal direction where the first inlethole 5 and the second outlet hole 8 are located and extending toward theedge (the lower side) in the longitudinal direction where the secondinlet hole 7 and the second outlet hole 8 are located in such a manneras to gradually curve toward the edge (the right side) in the lateraldirection near the second outlet hole 8. Specifically, in FIG. 13, thesealing portion 11 is formed to gradually curve to the right in adownward direction.

The sealing portion 11 facilitates the first fluid which has flowedthrough the entrance region 10 to spread toward the edge (the rightside) in the lateral direction near the second outlet hole 8. That is,the entrance region 10 and the sealing portion 11 provide a guidingeffect for guiding the first fluid toward the edge (the right side) inthe lateral direction near the second outlet hole 8. This guiding effectcan prevent the first fluid from stagnating around the sealing portion11 or near the periphery of the plates 2 and 3, thereby enhancing theheat exchange capability. This guiding effect can also reduce thepressure loss of the first fluid. That is, the plate heat exchanger 20with enhanced performance can be provided.

When the sealing portion 11 is provided around the second outlet hole 8in a circular shape, as is normally done, it is necessary to provide adistribution facilitating member around the first inlet hole 5 so as toprevent the first fluid from drifting. The distribution facilitatingmember is formed, for example, in a complex shape such as a radialshape. Thus, it is difficult to manufacture the plate heat exchanger 20including the distribution facilitating member. However, the plate heatexchanger 20 according to the third embodiment simply includes thesealing portion 11 which is curved, and thus is simple to manufacture.For this reason, the plate heat exchanger 20 according to the thirdembodiment is highly suitable for mass production.

FIG. 14 is a diagram describing the corrugations 9 in the first plate 3in which the inlet and outlet holes are positioned nearer to the fourcorners. FIG. 15 is a diagram showing the corrugations 9 in the secondplate 2 in which the inlet and outlet holes are positioned nearer to thefour corners. FIG. 16 is a diagram showing the corrugations 9 in thefirst plate 3 in which the inlet and outlet holes are positioned nearerto the four corners.

As has been described in the first embodiment, each of the plates 2 and3 includes the corrugations 9 arranged in a plurality of longitudinalarrays, the corrugations 9 having the ends 13 at both sides in thelateral direction and also having the turning points 12 longitudinallymisaligned with respect to the corresponding ends 13 at both sides, sothat the corrugations 9 are V-shaped. The turning points 12 of thecorrugations 9 in the plates 2 and 3 shown in FIGS. 3 and 4 arepositioned at the lateral center. That is, the corrugations 9 are formedin a bilaterally symmetrical manner.

In the plates 2 and 3 shown in FIG. 14, the diameters of the first inletand outlet holes are smaller than the diameters of the second inlet andoutlet holes. That is, in FIG. 14, the diameters of the first inlet hole5 and the first outlet hole 6 are smaller than the diameters of thesecond inlet hole 7 and the second outlet hole 8. For this reason, ifthe turning points 12 are positioned at the lateral center as in theplates 2 and 3 shown in FIGS. 3 and 4, this will create regions wherethe corrugations 9 are not foimed near the first inlet hole 5 and thefirst outlet hole 6. Thus, in the regions near the first inlet hole 5and the first outlet hole 6, the corrugations 9 are formed by shiftingthe positions of the turning points 12 of the corrugations 9 nearer tothe first inlet hole 5 and the first outlet hole 6, respectively. Thatis, as shown in FIG. 14, a line 15 linking the turning points 12 of thecorrugations 9 is defined in a gradual curve, curving toward the firstinlet hole 5 and the first outlet hole 6, respectively, from a centerline 14 at the lateral center.

In this way, the corrugations 9 can also be formed in the regions nearthe first inlet hole 5 and the first outlet hole 6, so that the heattransfer area is increased. Accordingly, the heat exchange capability ofthe plate heat exchanger 20 is enhanced. The plates 2 are joined withthe respective adjacent plates 3 at portions where the corrugations 9are formed. Generally speaking, the plates 2 and 3 are prone toseparation from one another in regions near the inlet and outlet holes.However, by forming the corrugations 9 also in the regions near theinlet and outlet holes, the joining points between the plates 2 and 3are increased in number, so that the plates 2 and 3 can be preventedfrom separating from one another. Further, the position of each turningpoint 12 of the corrugations 9 gradually moves from the first inlet hole5 toward the lateral center and from the lateral center toward the firstoutlet hole 6. This makes it possible to smoothly transfer the firstfluid entered from the first inlet hole 5 to the lateral center and fromthe lateral center to the first outlet hole 6. Accordingly, the pressureloss of the first fluid can be reduced.

As in the first plate 3, the corrugations 9 are also formed in thesecond plate 2 by shifting the positions of the turning points 12 nearerto the first inlet hole 5 and the first outlet hole 6 in the regionsnear the first inlet hole 5 and the first outlet hole 6 having smallerdiameters, respectively, as shown in FIG. 16.

Fourth Embodiment

In a fourth embodiment, there will be described the plate heat exchanger20 in which the shapes of the first inlet and outlet holes and thesecond inlet and outlet holes are modified.

FIGS. 17 to 19 are diagrams showing the plates 2 and 3 in which thefirst inlet and outlet holes are shaped differently from the secondinlet and outlet holes while maintaining required opening areas.

In FIG. 17, the first inlet and outlet holes and the second inlet andoutlet holes are formed in approximately elliptical shapes differentfrom each other. In FIG. 18, a circle is divided into two such that oneof the two portions is the first inlet or outlet hole and the otherportion is the second outlet or inlet hole. In FIG. 19, an approximatelyrectangular shape is divided into two such that one of the two portionsis the first inlet or outlet hole and the other portion is the secondoutlet or inlet hole.

In FIGS. 17 to 19, the diameters of the first inlet and outlet holes aresmaller than the diameters of the second inlet and outlet holes.

FIG. 20 is a diagram comparing a case in which the first inlet andoutlet holes and the second inlet and outlet holes are identical inshape, and a case in which the first inlet and outlet holes and thesecond inlet and outlet holes are different in shape. FIG. 20 shows thelongitudinal side of the plates 2 and 3 where the first outlet hole 6and the second inlet hole 7 are located. FIG. 20 (a) shows the plates 2and 3 in which the first outlet hole 6 and the second inlet hole 7 areboth circularly shaped. On the other hand, FIG. 20 (b) shows the plates2 and 3 in which a circle is divided into two such that one of the twoportions is the first inlet or outlet hole and the other portion is thesecond outlet or inlet hole, as shown in FIG. 18. In FIG. 20 (a) andFIG. 20 (b), the diameters of the first inlet and outlet holes aresmaller than the diameters of the second inlet and outlet holes.

The first outlet hole 6 shown. in FIG. 20 (a) is a circle having adiameter of “12 mm”, and the second inlet hole 7 is a circle having adiameter of “28 mm”. The distance between the first outlet hole 6 andthe second inlet hole 7 is “3 mm”. Accordingly, the opening area of thefirst outlet hole 6 is “36 πm²”, and the opening area of the secondinlet hole 7 is “196 πm²”. The length from the edge of the first outlethole 6 to the edge of the second inlet hole 7 is “43 mm”.

On the other hand, the first outlet hole 6 shown in FIG. 20 (b) is aquarter of a circle having a diameter of “24 mm”, and the second inlethole 7 is three-quarters of a circle of “31 mm”. The distance betweenthe first outlet hole 6 and the second inlet hole 7 is “3 mm”.Accordingly, the opening area of the first outlet hole 6 is “36 πm²”,and the opening area of the second inlet hole 7 is “192 πm²”. The lengthfrom the edge of the first outlet hole 6 to the edge of the second inlethole 7 is “31 mm”.

That is, the opening area of the first outlet hole 6 shown in FIG. 20(a) and the opening area of the second inlet hole 7 shown in FIG. 20 (b)are both “36 πm²” and thus are the same. The opening area of the firstoutlet hole 6 shown in FIG. 20 (a) and the opening area of the secondinlet hole 7 shown in FIG. 20 (b) are “196 πm²” and “192 πm²”,respectively, and thus are approximately the same. However, the lengthfrom the edge of the first outlet hole 6 to the edge of the second inlethole 7 is “43 mm” in the plates 2 and 3 shown in FIG. 20( a), whereasthis length is “31 mm” in the plates 2 and 3 shown in FIG. 20 (b). Thatis, the length from the edge of the first outlet hole 6 to the edge ofthe second inlet hole 7 is significantly shorter in the plates 2 and 3shown in FIG. 20 (b) than in the plates 2 and 3 shown in FIG. 20 (a).This means that by forming the first outlet hole 6 and the second inlethole 7 as shown in FIG. 20 (b), the lateral length of the plates 2 and 3can be significantly shortened while maintaining the required openingareas of the first outlet hole 6 and the second inlet hole 7.

FIGS. 21 to 24 are diagrams showing the plates 2 and 3 in which thefirst inlet and outlet holes and the second inlet and outlet holes areformed in identical non-circular shapes while maintaining the requiredopening areas.

In FIG. 21, the first inlet and outlet holes and the second inlet andoutlet holes are formed identically in an approximately ellipticalshape. In FIGS. 22 and 23, the first inlet and outlet holes and thesecond inlet and outlet holes are formed identically in a fan-likeshape. In FIG. 24, the first inlet and outlet holes, and the secondinlet and outlet holes are formed identically in a star-like shape.

By forming the first inlet and outlet holes and the second inlet andoutlet holes in various combinations of shapes as described above, thelateral length of the plates 2 and 3 can be shortened. Thus, the effectsdescribed in the first embodiment can be obtained. When the first inletand outlet holes and the second inlet and outlet holes are shapedidentically, the plate heat exchanger 20 can be configured with theplates 2 and 3 of a single type.

Fifth Embodiment

In a fifth embodiment, there will be described a heating and hot watersystem 29, which is a usage example of the plate heat exchanger 20described in the above embodiments.

FIG. 25 is a diagram showing the heating and hot water system 29.

The heating and hot water system 29 includes a compressor 21, the plateheat exchanger 20, an expansion valve 22, a heat exchanger 23, a waterheater 24, a heater 25, a refrigerant path 26, and a water path 27. Theplate heat exchanger 20 here is the plate heat exchanger 20 described inthe above embodiments. The compressor 21, the plate heat exchanger 20,the expansion valve 22, the heat exchanger 23, and the refrigerant path26 constitute a heat exchange system 28.

A refrigerant flows through the refrigerant path 26 by circulatingsequentially through the compressor 21, the plate heat exchanger 20, theexpansion valve 22, and the heat exchanger 23. As described above, thecompressor 21 compresses the refrigerant. The plate heat exchanger 20exchanges heat between the refrigerant compressed by the compressor 21and a fluid (water in this case) flowing through the water path 27.Here, the refrigerant is cooled and the water is warmed by heat exchangein the plate heat exchanger 20. The expansion valve 22 controlsexpansion of the refrigerant heat-exchanged by the plate heat exchanger20. The heat exchanger 23 exchanges heat between air and the refrigerantexpanded based on control by the expansion valve 22. Here, therefrigerant is warmed and the air is cooled by heat exchange in the heatexchanger 23. Then, the warmed refrigerant enters the compressor 21.

On the other hand, the water flows through the water path 27 among theplate heat exchanger 20, the water heater 24, and the heater 25. Asdescribed above, the water is warmed by heat exchange in the plate heatexchanger 20. Then, the warmed water flows to the water heater 24 or theheater 25. The water for hot-water supply may be different from thewater heat-exchanged by the plate heat exchanger 20. That is, the waterheater 24 or the like may further exchange heat between the waterflowing through the water path 27 and the water for hot-water supply.

The plate heat exchanger 20 described in the above embodiments providesenhanced strength, a compact and lightweight structure, and enhancedefficiency. Thus, the heat exchange system 28 using the plate heatexchanger 20 described in the above embodiments also provides enhancedefficiency. The heating and hot water system 29 using the heat exchangesystem 28 also provides enhanced efficiency.

Here, a heat exchange system (an air-to-water (ATW) system) has beendescribed, wherein the plate heat exchanger 20 described in the aboveembodiments heats water by using a compressed refrigerant. However, theimplementation is not limited to this, and a refrigeration cycle (arefrigeration air conditioner) may be configured for exchanging heat byusing the plate heat exchanger 20 described in the above embodiments soas to heat or cool a fluid such as air.

The above embodiments are summarized as follows:

The plate heat exchanger 20 is configured with a plurality of stackedplates such that flow holes which act as inlets or outlets for a fluidare formed at four corners of each plate, and inlet ducts and outletducts are provided in the plurality of stacked plates. The plate heatexchanger 20 is characterized in that the ratio of the height (H) to thewidth (W) of the plates is in a range of 4 to 6.5.

The plate heat exchanger 20 is configured with a plurality of stackedplates such that flow holes which act as inlets or outlets for a fluidare formed at four corners of each plate, and inlet ducts and outletducts are provided in the plurality of stacked plates. The plate heatexchanger 20 is characterized in that the widthwise distance betweeneach of the first and second fluid inlets and outlets and the peripheryof the plate is 3 to 6% of the width (W) of the plate.

The plate heat exchanger 20 is configured with a plurality of stackedplates such that flow holes which act as inlets or outlets for a fluidare formed at four corners of each plate, and inlet ducts and outletducts are provided in the plurality of stacked plates. The plate heatexchanger 20 is characterized in that the widthwise distance betweeneach of the first and second fluid inlets and'outlets and the peripheryof the plate is 3 to 5.6 mm.

The plate heat exchanger 20 is configured with a plurality of stackedplates such that flow holes which act as inlets or outlets for a fluidare formed at four corners of each plate, and inlet ducts and outletducts are provided in the plurality of stacked plates. The plate heatexchanger 20 is characterized in that the diameters of the first inletand outlet are differently sized from the diameters of the second fluidinlet and outlet.

The plate heat exchanger 20 is configured with a plurality of stackedplates such that flow holes which act as inlets or outlets for a fluidare formed at four corners of each plate, and inlet ducts and outletducts are provided in the plurality of stacked plates. The plate heatexchanger 20 is characterized in that the centers of the first fluidinlet and outlet are misaligned with the centers of the second fluidinlet and outlet such that the fluid inlets and outlets are shiftednearer to the periphery of the plate.

The plate heat exchanger 20 is configured with a plurality of stackedplates such that flow holes which act as inlets or outlets for a fluidare formed at four corners of each plate, and inlet ducts and outletducts are provided in the plurality of stacked plates. The plate heatexchanger 20 is characterized in that crest portions formed at turningpoints of waves are arranged to gradually curve from the center of theplate such that the turning points of the waves are formed in regionsnear the inlet and outlet.

The plate heat exchanger 20 is configured with a plurality of stackedplates such that flow holes which act as inlets or outlets for a fluidare formed at four corners of each plate, and inlet ducts and outletducts are provided in the plurality of stacked plates. The plate heatexchanger 20 is characterized in that the centers of the diameters ofthe first fluid inlet and outlet are misaligned with the centers of thediameters of the second inlet and outlet, and the first inlet and outletand the second inlet and outlet are formed in a combination of differentshapes such as circular shapes or polygonal shapes while maintainingrequired opening areas according to a processing flow amount of thesecond fluid.

The plate heat exchanger 20 is configured with a plurality of stackedplates such that flow holes which act as inlets or outlets for a fluidare formed at four corners of each plate, and inlet ducts and outletducts are provided in the plurality of stacked plates. The plate heatexchanger 20 is characterized in that the first inlet and outlet and thesecond inlet and outlet are formed in a combination of an identicalshape such as a circular shape or a polygonal shape while maintainingrequired opening areas according to a processing flow amount of thesecond fluid.

REFERENCE SIGNS LIST

1, 4: reinforcement side plates, 2: second plate, 3: first plate, 5:first inlet hole, 6: first outlet hole, 7: second inlet hole, 8: secondoutlet hole, 9: corrugations, 10: entrance region, 11: sealing portion,12: turning point, 13: ends, 14: center line in the lateral direction,15: line linking the turning points 12, 20: plate heat exchanger, 21:compressor, 22: expansion valve, 23: heat exchanger, 24: water heater,25: heater, 26: refrigerant path, 27: water path, 28: heat exchangesystem

1. A plate heat exchanger configured with a plurality of stacked plates,wherein each plate of the plurality of stacked plates includes: a firstinlet hole which acts as an inlet for a first fluid, the first inlethole being located near one edge in a longitudinal direction; a firstoutlet hole which acts as an outlet for the first fluid, the firstoutlet hole being located near another edge opposite from the firstinlet hole in the longitudinal direction; a second inlet hole which actsas an inlet for a second fluid, the second inlet hole being located nearone edge in the longitudinal direction; and a second outlet hole whichacts as an outlet for the second fluid, the second outlet hole beinglocated near another edge opposite from the second inlet hole in thelongitudinal direction, wherein the each plate and an adjacent platedefine therebetween either one of a first flow path and a second flowpath, the first flow path passing the first fluid entered from the firstinlet hole to the first outlet hole such that the first fluid spreads ina lateral direction, and the second flow path passing the second fluidentered from the second inlet hole to the second outlet hole such thatthe second fluid spreads in the lateral direction, and the each plateexchanges heat between the first fluid flowing through the first flowpath and the second fluid flowing through the second flow path, andwherein the each plate is configured such that a length in thelongitudinal direction is 4 or more times a length in the lateraldirection.
 2. The plate heat exchanger according to claim 1, whereineach of a length from the first inlet hole to a plate edge proximate tothe first inlet hole in the lateral direction, a length from the firstoutlet hole to a plate edge proximate to the first outlet hole in thelateral direction, a length from the second inlet hole to a plate edgeproximate to the second inlet hole in the lateral direction, and alength from the second outlet hole to a plate edge proximate to thesecond outlet hole in the lateral direction is not more than 6 percentof the length in the lateral direction.
 3. The plate heat exchangeraccording to claim 1, wherein each of a length from the first inlet holeto a plate edge proximate to the first inlet hole in the lateraldirection, a length from the first outlet hole to a plate edge proximateto the first outlet hole in the lateral direction, a length from thesecond inlet hole to a plate edge proximate to the second inlet hole inthe lateral direction, and a length from the second outlet hole to aplate edge proximate to the second outlet hole in the lateral directionis not more than 5.6 mm.
 4. The plate heat exchanger according to claim1, wherein each of an opening area of the first inlet hole and anopening area of the first outlet hole is smaller than either of anopening area of the second inlet hole and an opening area of the secondoutlet hole.
 5. The plate heat exchanger according to claim 4, wherein acenter of the first inlet hole and a center of the first outlet hole arepositioned nearer to a plate edge relative to a center of the secondinlet hole and a center of the second outlet hole.
 6. The plate heatexchanger according to claim 4, wherein a first plate and a second plateare stacked alternately, wherein the first inlet hole and the secondoutlet hole are positioned near a same edge in the longitudinaldirection, and wherein the first plate includes a sealing portion forpreventing a fluid entered from the first inlet hole from flowing to thesecond outlet hole, the sealing portion being formed as a protrusionraised in a stacking direction of the plurality of stacked plates suchthat the sealing portion extends from near the edge where the firstinlet hole and the second outlet hole are located toward an oppositeedge in the longitudinal direction, so as to gradually approach an edgein the lateral direction near the second outlet hole.
 7. The plate heatexchanger according to claim 4, wherein the each plate includes V-shapedconvex portions and concave portions arranged in a plurality of arraysin the longitudinal direction, each of the convex portions and concaveportions having ends at both ends in the lateral direction and alsohaving a turning point longitudinally misaligned with the ends, so thatthe convex portions and concave portions are formed in a V shape, andwherein, in a vicinity of at least either hole of the first inlet holeand the first outlet hole, the V-shaped convex portions and concaveportions are formed such that a position of the turning point isgradually shifted toward the either hole away from a center in thelateral direction as a position of each of the V-shaped convex portionsand concave portions becomes nearer to the each hole.
 8. The plate heatexchanger according to claim 4, wherein the plurality of stacked platesare stacked such that the first inlet hole of the each plate is alignedwith first inlet holes of other plates, so that the first fluidsequentially flows from the first inlet hole of the each plate stackedat one side of the stacking direction into the first inlet hole of theeach plate stacked at another side of the stacking direction, andwherein the nearer the each plate of the plurality of stacked plates isto the one side from which the first fluid enters, the smaller adiameter of the first inlet hole.
 9. The plate heat exchanger accordingto claim 1, wherein the first inlet hole and the second outlet hole areformed near a same edge in the longitudinal direction, and the secondinlet hole and the first outlet hole are formed near a same edge in thelongitudinal direction, and wherein a shape of the first inlet hole isdifferent from a shape of the second outlet hole, and a shape of thesecond inlet hole is different from a shape of the first outlet hole.10. The plate heat exchanger according to claim 9, wherein the firstinlet hole and the second outlet hole are formed by dividing one hole ofa circular, elliptical, or polygonal shape into two holes, and whereinthe second inlet hole and the first outlet hole are formed by dividingone hole of a circular, elliptical, or polygonal shape into two holes.11. A refrigeration air conditioner comprising the plate heat exchangeraccording to claim
 1. 12. A plate heat exchanger configured with aplurality of stacked plates, wherein each plate of the plurality ofstacked plates includes: a first inlet hole which acts as an inlet for afirst fluid, the first inlet hole being located near one edge in thelongitudinal direction; a first outlet hole which acts as an outlet forthe first fluid, the first outlet hole being located near another edgeopposite from the first inlet hole in the longitudinal direction; asecond inlet hole which acts as an inlet for a second fluid, the secondinlet hole being located near one edge in the longitudinal direction;and a second outlet hole which acts as an outlet for the second fluid,the second outlet hole being located near another edge opposite from thesecond inlet hole in the longitudinal direction, wherein the each plateand an adjacent plate define therebetween either one of a first flowpath and a second flow path, the first flow path passing the first fluidentered from the first inlet hole to the first outlet hole such that thefirst fluid spreads in a lateral direction, and the second flow pathpassing the second fluid entered from the second inlet hole to thesecond outlet hole such that the second fluid spreads in the lateraldirection, and the each plate exchanges heat between the first fluidflowing through the first flow path and the second fluid flowing throughthe second flow path, and wherein each of a length from the first inlethole to a plate edge proximate to the first inlet hole in the lateraldirection, a length from the first outlet hole to a plate edge proximateto the first outlet hole in the lateral direction, a length from thesecond inlet hole to a plate edge proximate to the second inlet hole inthe lateral direction, and a length from the second outlet hole to aplate edge proximate to the second outlet hole in the lateral directionis not more than 6 percent of a length in the lateral direction.
 13. Aplate heat exchanger configured with a plurality of stacked plates,wherein each plate of the plurality of stacked plates includes: a firstinlet hole which acts as an inlet for a first fluid, the first inlethole being located near one edge in the longitudinal direction; a firstoutlet hole which acts as an outlet for the first fluid, the firstoutlet hole being located near another edge opposite from the firstinlet hole in the longitudinal direction; a second inlet hole which actsas an inlet for a second fluid, the second inlet hole being located nearone edge in the longitudinal direction; and a second outlet hole whichacts as an outlet for the second fluid, the second outlet hole beinglocated near another edge opposite from the second inlet hole in thelongitudinal direction, wherein the each plate and an adjacent platedefine therebetween either one of a first flow path and a second flowpath, the first flow path passing the first fluid entered from the firstinlet hole to the first outlet hole such that the first fluid spreads ina lateral direction, and the second flow path passing the second fluidentered from the second inlet hole to the second outlet hole such thatthe second fluid spreads in the lateral direction, and the each plateexchanges heat between the first fluid flowing through the first flowpath and the second fluid flowing through the second flow path, andwherein each of a length from the first inlet hole to a plate edgeproximate to the first inlet hole in the lateral direction, a lengthfrom the first outlet hole to a plate edge proximate to the first outlethole in the lateral direction, a length from the second inlet hole to aplate edge proximate to the second inlet hole in the lateral direction,and a length from the second outlet hole to a plate edge proximate tothe second outlet hole in the lateral direction is not more than 5.6 mm.